1. Field of the Invention
The present invention relates to a device for simultaneously reducing the evaporative emissions from a fuel tank and the control of fuel travelings between the tank and the fuel filler pipe.
2. Description of the Related Art
The present invention is intended to simultaneously address two areas of automotive fuel hank design. The first area is the unwanted release of liquid fuel from a fuel system during refueling. The second area is a reduction in evaporative emissions of fuel vapor during refueling.
Automotive fuel tanks contain a fuel filler pipe which receives fuel from a fuel nozzle. Automatic fuel pump nozzles contain sensors to sense an increased pressure within the fuel filler pipe. When some automotive fuel tanks are over-filled or filled too quickly, the fuel pump abruptly shuts the flow of fuel and causes a condition commonly referred to as "spit-back". Spit-back is the term used to describe fuel exiting the fuel filler pipe and possibly the fuel inlet door. Spit-back is caused by an increased pressure within the fuel tank being relieved through the fuel filler pipe rather than the fuel sensing tube.
A variety of devices have been used to reduce spit-back. Commonly used devices include valves, labyrinths and baffles. Valves are opened by the weight of the fuel as it enters the fuel tank. They are generally located at the juncture between the fuel filler pipe and fuel tank interior. The weight of the fuel causes the valve to open and admit fuel. Once the fuel tank is filled, the valve closes to reduce or prevent spit-back. Valves of this type are illustrated in U.S. Pat. No. 4,760,933. It is difficult to adjust the valve opening force without inducing premature fuel shut-off.
Labyrinths and baffles rely on the shape of the fuel return line to reduce spit-back. An example of a baffle design is illustrated in U.S. Pat. No. 4,274,549. Labyrinth construction is generally more complicated to fabricate and requires more space within the fuel tank.
The other object of the invention is to reduce the vapor generated within the tank during refueling. Fuel vapor is generated when liquid fuel impacts either the bottom surface of the fuel tank or the rising level of the fuel within the tank. The speed, angle and force with which the fuel impacts the fuel tank bottom or fuel surface affects the amount of fuel vapor generated during refueling. Although not specifically intended to reduce fuel vapor, the device illustrated in U.S. Pat. No. 4,501,374 reduces the speed and force with which fuel added to a tank impacts the fuel surface. The U.S. Pat. No. 4,501,374 teaches a check valve which extends below the surface of the fuel. Check valves of this type would have the effect of reducing the fuel velocity as it enters the tank.
Problems with this type of check valves is again premature shut-off of the fuel nozzle during refueling. Fuel entering the fuel filler pipe must overcome the closing force of the check valve as well as the force of displacing the fuel within the device below the fuel surface. The level of fuel in the fuel filler pipe often exceeds the level of fuel within the tank. The fuel nozzle senses a change in pressure as little as 0.01 psi to signal the fuel nozzle to shut-off. The rising level of fuel within the fuel filler pipe causes an increased pressure and triggers the fuel nozzle to shut-off before the tank is filled.